California Olive Farmers Create Pollinator Habitats to Boost Biodiversity

California olive grow­ers are increas­ingly com­bat­ing the impacts of cli­mate change by cul­ti­vat­ing native plants to cre­ate habi­tats for ben­e­fi­cial insects and pol­li­na­tors.

Since the 1980s, the Western Monarch but­ter­fly pop­u­la­tion has declined by more than 95 per­cent. More gen­er­ally, insect pol­li­na­tor pop­u­la­tions have dropped, likely due to cli­mate change, pes­ti­cides and habi­tat degra­da­tion.

The Xerces Society for Invertebrate Conservation is among the groups fight­ing against the decline in pol­li­na­tors, pro­vid­ing cli­mate-smart native plants to project part­ners.

Native habi­tat kits of more than 100,000 plants have already been pro­vided to 144 farm­ing part­ners in California between 2019 and 2021.

“The Xerces habi­tat kits pro­gram in California matches peo­ple and places who want to plant and care for pol­li­na­tor and ben­e­fi­cial insect habi­tat with trans­plants of native plants with high con­ser­va­tion value,” Stephanie Frischie, an agron­o­mist for Xerces, told Olive Oil Times.

She added that the com­pany pro­vides tech­ni­cal assis­tance to farm­ers to make sure the solu­tions are long-term and sus­tain­able. The com­pany also helps farm­ers iden­tify the most well-suited species to their par­tic­u­lar loca­tion and source them locally to rebuild endemic habi­tats.

While Frischie advises farm­ers across Canada and the United States, Frischie said some of her ear­li­est research focused on olive groves in Spain ​“through on-farm habi­tat research and projects, such as study­ing the suit­abil­ity of native cover crops for olive orchards in Spain.”

“We found nearly a dozen high-pri­or­ity species, and I worked with a native seed grower to develop the sup­ply of those cover crop species,” Frischie added. ​“I con­tinue to do this type of work in my role at the Xerces, increas­ing the seed sup­ply of plants that are of high value to pol­li­na­tors and other insects so more habi­tat can be cre­ated to add or enhance bio­di­ver­sity on farms.”

In Yolo County, Temecula Olive Oil Company is the hub where farm­ers can pick up Xerces habi­tat kits.

“Even though olive trees evolved before the dawn of insects and do not need them for pol­li­na­tion – they are anemophilous [spread­ing pollen via the wind] – work­ing with Xerces and cre­at­ing more native pol­li­na­tors is impor­tant for many rea­sons,” Thom Curry, the owner of Temecula Olive Oil Company, told Olive Oil Times.

“The most impor­tant ben­e­fits are plant and ani­mal diver­sity,” he added. ​“A diverse com­mu­nity is much more resilient and healthy. Over time, our mono­cul­tural farm­ing prac­tices have had a detri­men­tal effect on the diver­sity and, there­fore, the over­all biome health.”

In the San Joaquin Valley, Don Cameron, the vice pres­i­dent and gen­eral man­ager of Terranova Ranch, praised the kits. He said they helped him deter­mine which pol­li­na­tors would do well in his grove, tak­ing some of the risk out of the invest­ment.

“I believe that any­thing we can do to increase the pop­u­la­tion of native pol­li­na­tors not only ben­e­fits the olives but a wide range of other agri­cul­tural crops that are depen­dent on insect pol­li­na­tion,” he told Olive Oil Times.

According to Frischie, cli­mate-smart native plants have far-reach­ing ben­e­fits for farm­ers and pro­duc­ers.

“The habi­tat sup­ports birds and other wildlife, adds to soil car­bon and organic mat­ter and can improve water infil­tra­tion and water stor­age capac­ity of the soil,” she said. ​“There are typ­i­cally more than 12 species of plants in each kit, which also add col­or­ful leaves and flow­ers to farm­scapes.”

For olive farm­ers specif­i­cally, Frishie said that habi­tat kit also cre­ates nat­ural envi­ron­ments for preda­tors of com­mon olive pests.

“Cover crops and recov­er­ing native pol­li­na­tor sites help improve the tilth of the soil and lessen the amount of out­side inputs,” Curry added. ​“Studies also show that these prac­tices also improve the amount of car­bon sequestered by the olive grove.”

Farmers take dif­fer­ent approaches to where to plant the kits.

“Depending on the farm, the habi­tat kits may be planted along field edges or in other places near the olive trees or other crops,” Frischie said. ​“For orchard species, cover crops in the lanes between tree rows are another way to add ben­e­fi­cial habi­tat to farms.”

“Not only is there a ben­e­fit to the native pol­li­na­tors in the area by pro­vid­ing a food source,” Cameron added, ​“but for instance, in plant­ing native pol­li­na­tor hedgerows, we have seen other ben­e­fits, includ­ing ero­sion con­trol in areas with slopes and sandier soils that main­tain the integrity of our lev­ees and road­sides.”

Some myths per­sist about native plants, pol­li­na­tion and restora­tion of insect habi­tats. For exam­ple, Curry said some peo­ple erro­neously assume that European and Africanized honey bees are the only or most effec­tive pol­li­na­tors.

“These insects are inter­lop­ers and tend to push out native pol­li­na­tors with the assis­tance of the human prop­a­ga­tion of them,” he said. ​“Creating a stronger native pol­li­na­tor pop­u­la­tion helps the native and non-native plants thrive much bet­ter.”

Some raise con­cerns that cul­ti­vat­ing native plant habi­tats for pol­li­na­tors in the olive groves could have side effects.

“There’s some con­cern that the habi­tat areas may lead to larger pop­u­la­tions of rab­bits, hares or other rodents that could dam­age crops or farm infra­struc­ture, and snakes,” Frischie said. ​“I’m not aware of evi­dence that shows these ben­e­fi­cial insect plant­i­ngs result in higher inci­dences of dam­age from these ani­mals.”

She added that October and November are an oppor­tune moment for olive grow­ers statewide to find the suit­able kit for them and begin plant­ing.

“I am sure that it will become much more main­stream due to the efforts of Xerces and other such pro­grams,” Curry said. ​“It seems that the prac­tice is really tak­ing off in the main­stream farm­ing com­mu­nity.”

Cameron agreed. ​“I believe that by get­ting these kits out to olive grow­ers, they will find sim­i­lar attrib­utes to what I have seen and will con­tinue to invest in expand­ing projects on their farms to diver­sify habi­tats,” he con­cluded.

• Lodi Wine Growers
• Yolo County Resource Conservation District